1. Field of the Invention
The invention relates to payloads consisting of multiple and/or heterogeneous warheads such as sub-munitions placed in a missile rotating on its longitudinal axis. These payloads have to be released in trajectory and, hence, their arrangement inside the missile is designed so as to make the constituent elements separate at the moment that they are dropped. The invention is more especially suited to resolving problems concerning missiles that consist of mortar shells rotating at very high speed (more than 1000 rpm).
2. Description of the Prior Art
In a mortar shell, the mechanical stresses which are caused by acceleration and to which the shell is subjected at the moment of firing are particularly intense, and it is very difficult for the mechanical structure placed in the shell to withstand them: if several sub-munitions are placed behind one another, with the first sub-munition resting on the second, the second on the third and so on, the pressure to which the last sub-munition is subjected by the other sub-munitions at the moment of firing is such that this last sub-munition cannot withstand this mechanical stress.
It has already been envisaged that each sub-munition could be reinforced in a manner depending on the row occupied by it in the stack, within the missile, so as to withstand the pressure exerted by the preceding sub-munitions. The major disadvantage of this method is that the place within each sub-munition, intended for the very function of this sub-munition, keeps diminishing or even becomes non-existent.
One approach already proposed to resolve this problem consists in a stacking of sub-munitions wherein each sub-munition has, as shown in FIG. 1, a supporting element consisting of two ties 2A and 2B which can be separated at the moment of dropping to release the sub-munition. These two ties each have a reinforcement piece 3A and 3B at their rear to support the sub-munition at the starting instant. Thus, the inertial forces when the shot is fired, due to each sub-munition, are supported solely by their two respective ties. Each tie is in contact with the following one. The forces thus accumulated are transmitted to the back 4 of the missile.
One of the disadvantages of this type of assembly is shown in FIG. 2. FIG. 2 shows the same elements as those shown in FIG. 1, but during the dropping stage. Ejection takes place through the rear of the casing 5 of the projectile, along the longitudinal axis X, X', the back 4 being detached from the casing. After this, come the last two ties 2A and 2B supporting the sub-munition 6. It is seen that the rear portions 3A and 3B of the last two ties are subjected to centrifugal force due to the high rotational speed of the entire missile, the sub-munitions and their ties. When a sufficient length of the ties has been released from the casing 5, these ties move away from each other and create a jamming which blocks them between their own sub-munitions 6 and the casing 5 of the missile, thus slowing down the dropping operation and all the following sub-munitions and thus possibly damaging the sub-munitions.
Another disadvantage of this system is that, under the effect of the rotational speed of the entire missile on its longitudinal axis, the ties 2A and 2B, subjected to the centrifugal force, are pushed against the internal wall of the casing and create frictional forces between the ties and the casing. This considerably slows down any longitudinal translation of the sub-munitions, surrounded by their ties, and hinders the dropping of the sub-munitions.
An object of the invention is to remove these drawbacks by creating a new system to maintain the payload within the missile while, at the same time, enabling this payload to be easily dropped.